Hundreds of thousands of residents were evacuated from within a 20 km radius of the plant in the days after it was damaged by the March 11 earthquake and tsunami which disabled its crucial cooling systems.
As radioactive steam and smoke have wafted from the crippled site, and as hundreds of workers have battled to stabilise it, several foreign governments have urged their citizens to leave areas within 80 or even 100km of the plant.
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Japan's top government spokesman on Friday asked people remaining within the 30km zone to leave voluntarily, urging them to do so both for their own comfort and because radiation contamination may increase.
"It has become difficult for them to get daily necessities because the distribution of goods has stagnated," said Chief Cabinet Secretary Yukio Edano.
"It is desirable that they voluntarily evacuate. I cannot rule out the possibility that the government will issue an evacuation order for this area if the radiation level goes up further."
